A north temperate or subtropical family including 10 genera and about 115 species, found mainly in N. America and E. Asia, some of the members being ornamental. Closely related to Philadelphaceae from which it differs by the absence of stellate indumentum and the filaments which are slender and not toothed at the apex.

Acknowledgement: We are grateful to the United States Department of Agriculture for financing this research under P.L. 480.